The monitoring of a heart rate of a user for example by means of optical sensors is well known. Here, an optical sensor emits light into the skin of a user. The emitted light is scattered within the skin and reflected light exits the skin and is captured by an appropriate sensor. Based on the received signals from the sensor, the heart rate of a user can be determined.
US 2007/0244398 A1 discloses a heart rate monitor which uses ultrasound, infrared, pressure sensing, radio frequency or laser technology to measure a heart rate. Furthermore, this heart rate monitor also implements a power saving algorithm. This is performed by reducing or switching off the power of the sensors between expected heart beats.
US 2014/0073486 A1 discloses a lightweight wearable system adapted to collect various physiological data continuously from a user. The system comprises a heart rate monitor for monitoring the heart rate of the user. The system comprises a processing module that may receive data on the motion of the user using, for example, from an accelerometer. The processing module may process the motion data to determine a motion status of the user and, based on the motion status, may adjust the duty cycle of the heart rate monitor.
EP2457505A1 discloses a sensor array comprising one or more sensors. A sensor receives a stimulus and converts it into a data stream. Sensors may include sensors that are carried by the user such as a heart-rate monitor. One or more sensors in the sensor array may have a dynamic sampling rate. For example, if the stimulus measured by a sensor is different from the outcome predicted by some model or falls outside some threshold range, the sensor may increase or decrease its sampling rate in response.